What NOT to Plant with Tomatoes? 7 Plants To AVOID!

There are a few practices in agriculture that allow farmers to have better yields than usual. Naturally, there are also a handful of practices that yield opposite results.

When it comes to planting tomatoes, the same rule applies. There are a few arrangements that can help you increase production and some that can seriously hinder your end result. One such practice is known as companion planting

Companion planting of tomatoes, as with most plants, can help you get a stronger harvest when done right, or an uninspiring one when done wrong. In this post, we’re going to be looking into companion planting of tomatoes, and most importantly highlighting crops that you should never plant with them if you want to enjoy a bountiful harvest.


Understanding Companion Planting

As the name implies, companion planting is simply the practice of planting certain crops in near proximity to each other. Companion planting is done for plants that are known to offer a beneficial relationship with one another as they grow together.

The benefits companion plants offer each other can range from repelling insects, encouraging pollination, fostering improved nutrient uptake, and so on.

Conversely, as there are companion plants that offer beneficial relationships to one another, there are also companion plants that can be seriously harmful to each other.

When it comes to your tomato garden, you want the positive aspect of companion planting and not the negative. And how do you ensure you get positive? By knowing which crops to avoid planting with your tomatoes. 

What Not to Plant Near Tomatoes

The plants below have been identified to offer the most inhibitions for tomato growth. 

Cabbage (Brassicas) 🥬

Cabbage (and indeed all crops in the brassica family such as broccoli, kale, and others) should never be planted in a tomato garden or anywhere next to a tomato plant. In fact, so widely accepted is this rule that both families of plants are now considered mortal enemies in the gardening world.

do not plant cabbage near tomatoes

The reason for the animosity between brassicas and tomatoes is actually quite simple. Cabbages are seriously strong feeders that require plenty of nutrients all through their growing cycle. 

Tomatoes, while not as strong as cabbages and brassicas in general, are also regarded as very strong feeders. Having a battle of two heavy feeders in this manner is never advisable.

To make matters worse, cabbages are heavier feeders than tomatoes. This means that, when planted together and competition ensues, cabbages will almost always win that battle.

The result is that cabbages take all the nutrients leaving the tomatoes little to nothing to survive on. Tomatoes in this condition fail to grow, mature, or may end up not producing any fruit at all.

Corn 🌽

Cabbages are terrible companions for tomatoes thanks to their aggressive feeding nature. Corn, on the other hand, is a bad companion not because it is a heavy feeder, but because of its affinity towards attracting destructive pests.

never plant corn next to tomatoes

Corn earworm, for instance, is known for being a very devastating pest. The larvae of a corn earworm moth can completely decimate a crop. 

While corn earworms are strongly attracted to corn, it is not the only plant they feed on. In fact, another common name for these moths is “tomato fruitworm”. So while they are attracted by corn, a tomato plant in close vicinity will also suffer the consequence of their devastating presence.

Therefore, to avoid the complete destruction of your tomatoes, it is strongly advised that you avoid planting sweet corn in its vicinity.

Eggplant 🍆

Eggplants share a tricky relationship with tomatoes. While both can be quite beneficial to each other under the right conditions, all the benefits they may potentially offer are hugely negated by their mutual susceptibility to the same disease – early and late blight.

never plant eggplants and tomatoes together

Early blight causes tomato foliage to develop brown lesions that destroy leaf tissues. Once the leaves are dead, fewer nutrients are received thanks to a lack of photosynthesis, growth is inhibited, and fruits are left exposed to the sun.

Because both eggplants and tomatoes are susceptible to this disease, the possibility of onset is increased when both are near each other. Once one catches the disease, it spreads quickly to the other, ruining the harvest.

In fact, experts advise that eggplants and tomatoes should never be planted in the same soil within a 2-year interval.


Fennel is an example of a plant that is regarded as a bad companion for basically any crop in a garden. Most experts, in fact, advise that fennels should always be planted on their own or in a pot. 

do not plant fennel and tomatoes together

Seeing how established the incompatibility of fennels is, it might be a bit surprising to learn that there is actually a shortage of scientific evidence to back up the claim. Still, there is more than enough anecdotal evidence from farmers who have experienced the side effects.

Anyone who has been farming for a while would know that in agriculture, anecdotal experiences should never be taken lightly. What many gardeners have reported is that the roots of a fennel release chemicals that inhibit the growth of tomatoes and indeed other plants.

To add to the irony, carrots, which are related to fennels, are regarded as positive companions for tomatoes. 


Of all the crops on our list to never plant with tomatoes, walnuts are perhaps the most dangerous. Walnuts, you see, produce an allelopathic chemical known as juglone which seriously inhibits tomato growth.

do not plant tomatoes and walnuts together

What’s more, walnuts and tomatoes also share susceptibility to walnut wilt disease. Thankfully, planting walnuts near tomatoes is a highly unlikely occurrence.

But if the thought ever crosses your mind for a second, make sure you discard it immediately.


The relationship between dills and tomatoes is a rather interesting one. Unlike many of the plants on this list, dills have a sort of love-hate relationship with tomatoes.

do not plant tomatoes and dill

In the early stages of their growth in the same vicinity, dills are quite helpful and positive companions to tomatoes. They aid tomato growth by getting rid of pests. The problem, however, begins as both plants start to mature.

At this point, dills start to act as a competitor instead of a friend and thus inhibit tomato growth. It is advisable, for this reason, to refrain from planting dills and tomatoes near each other. 

Some have advised a method of taking advantage of the complex relationships between both plants. They advise that young dills and tomatoes can be planted next to each other, but as the dill begins to mature, they should be moved to another bed.

The ideal point for the transfer should be before they begin seeding. 

Potatoes 🥔

Potatoes and tomatoes share more than a rhyming name. They are also susceptible to the same diseases (quite similar to the scenario explored earlier between eggplants and tomatoes).

avoid planting tomatoes and potatoes

When planted together, the likelihood of a disease spreading from one plant to another becomes more profound. 

Additionally, planting tomatoes and potatoes together may lead to complications during harvesting. The harvesting process of potatoes can lead to damages to the tomato roots, thereby hindering growth and possibly killing the tomato plant in the end.

FAQ – What Not to Plant with Tomatoes

1. Is Tomato a Good Companion Plant?

Even though the list above focuses solely on which plants can be good or bad companions for tomatoes, it is worth mentioning that tomatoes can be very good companion plants for other crops. 

Examples of plants that benefit greatly from being planted near tomatoes include asparagus, chives, lettuce, marigolds, and roses (which they protect from black spot disease).

2. What are some examples of good companion plants for tomatoes?

The best companion plants for tomatoes are sweet basil, bush beans, cucumbers, collard greens, clovers, cow peas, radishes, sweet alyssum, amaranth, starflowers, carrots, and marigold flowers.

All of these plants help tomato growth either through pest control, disease prevention, soil enhancement, or weed reduction.

3. Are Tomatoes good companions for tomatoes?

Tomatoes planted together are usually not a big source of concern for each other in terms of competition. That said, this is only applicable in situations where there is enough spacing between the plants.

A sound recommendation is to ensure a spacing of about 18-24 inches between each tomato plant in the same garden. Of course, this is merely a general guideline.

A lot of factors such as location, exact plant type and garden type can influence the necessary spacing requirements.

Bottome line

Companion planting, also known as interplanting, is a gardening strategy capable of improving growth and increasing harvest yield. Sadly, when done wrong, it can also have serious consequences.

With every plant, the secret is to know which plants are good companion plants, and which plants are terrible ones. Above we have listed seven of the worst companion plants for tomatoes. Additionally, we have also provided examples of some good ones.

Make sure that you stay away from the negative companions, and you should be one step closer to a bountiful tomato harvest come harvest season.